According to an article in Redbook, the organic market is booming with about 70 percent of Americans buy organic food occasionally, and nearly one quarter buy it every week. The reason is simple: People want natural food that is healthier for their bodies and the environment.

While Organic food can be produced with certain synthetic ingredients, it must adhere to specific standards regulated by the USDA. Organic crops are generally grown without synthetic pesticides, artificial fertilizers, irradiation or biotechnology. According to the article, in the absence of pesticides and fertilizers, plants boost their production of the phytochemicals (vitamins and antioxidants) that strengthen their resistance to bugs and weeds. Pesticides have been shown to have carcinogenic and other adverse health effects in humans.

So why doesn't everyone eat organic all the time? The biggest reason is that organic food typically costs more.

The Environmental Working Group recognizes this conundrum and has responded by producing the Shopper's Guide to Pesticides. The guide ranks pesticide contamination for 47 popular fruits and vegetables based on an analysis of 87,000 tests for pesticides on these foods, conducted from 2000 to 2007 by the USDA and the FDA. Nearly all the studies used to create the list tested produce after it had been rinsed or peeled.

Results from the study show that people can lower their pesticide exposure by almost 80 percent by avoiding the top 12 most contaminated fruits and vegetables and eating the least contaminated instead. Eating the 12 most contaminated fruits and vegetables will expose a person to about 10 pesticides per day, on average. Eating the 15 least contaminated will expose a person to less than two pesticides per day.

Here is part of the list for the most contaminated: peaches, apples, sweet bell peppers, celery, and nectarines.

Here is part of the list for the least contaminated: onions, avocados, frozen sweet corn, pineapples, and mangoes.

Click here to see the full list and explanation. The best part of the guide is that it shows that eating healthy can be done without breaking the bank--it's all about making the right choices. I know I'm going to take this list with me whenever I go grocery shopping.